Melanoma

Cold exposure down-regulates zebrafish pigmentation

Vertebrates use adaptive mechanisms when exposed to physiologic stresses. However, the mechanisms of pigmentation regulation in response to physiologic stresses largely remain unclear. To address this issue, we developed a novel pigmentation model in adult zebrafish using coldwater exposure (cold zebrafish). When zebrafish were maintained at 17 °C, the pigmentation of their pigment stripes was reduced compared with zebrafish at 26.5 °C (normal zebrafish). In cold zebrafish, gene expression levels of tyrosinase and dopachrome tautomerase, which encode enzymes involved in melanogenesis, were down-regulated, suggesting that either down-regulation of melanin synthesis occurred or the number of melanophores decreased. Both regular and electron microscopic observation of zebrafish skin showed that the number of melanophores decreased, whereas aggregation of melanosomes was not changed in cold zebrafish compared with normal zebrafish. Taken together, we here show that cold exposure down-regulated adult zebrafish pigmentation through decreasing the number of melanophores and propose that the cold zebrafish model is a powerful tool for pigmentation research.

Whole recombinant yeast vaccine induces antitumor immunity and improves survival in a genetically engineered mouse model of melanoma

Malignant melanoma is one of the deadliest forms of skin cancer and its incidence is expected to rise over the next two decades. At present, there are no effective therapies for advanced melanoma. We have previously shown that administration of whole recombinant yeast expressing human MART-1 (hMART-IT) induces protective antimelanoma immunity in a B16F10 transplantable mouse model. In this study, we examine the effectiveness of the hMART-IT vaccine in a congenic strain of genetically engineered mouse model of melanoma, which recapitulates both the underlying genetics and the proper tumor microenvironment of naturally occurring melanoma. Subcutaneous administration of hMART-IT induced cytotoxicity against melanoma cells and antigen-specific production of Th1-specific cytokines by splenocytes. Weekly administration of hMART-IT significantly delayed the development of melanoma and prolonged the survival of mice compared with controls. Although histological analysis demonstrated diffuse infiltration of CD4(+) T cells and CD8(+) T cells, no reduction of regulatory T cells was observed, suggesting that hMART-IT cannot prevent immunotolerance in the tumor microenvironment. This study provides a proof of concept that genetically engineered mouse models lend valuable insights into immunotherapeutics being tested in the preclinical setting.

Hypopigmented scar formation after application of over-the-counter wart and mole removal cream

Today, there is a consensus that melanocytic nevi must not be removed by means of destructive modalities such as laser or electrodessication, since these procedures preclude histopathologic evaluation and may mask malignant transformation. Hence, a surgical excision with subsequent histopathologic evaluation remains the gold standard. Yet, patients that desire a removal of their melanocytic nevi for primary cosmetic reasons fear the formation of scars after surgical excision on the one hand and the private costs for excision and histopathologic evaluation on the other hand (as expenses for cosmetic surgery are no longer covered by health insurances). Accordingly, there is a vast market for "scar-free", "do-it-yourself" mole removers for unaware consumers. Here, we present two cases of patients that developed multiple hypopigmented scars after the application of a wart-and-mole removing cream that they had ordered from the internet.

Inverse expression states of the BRN2 and MITF transcription factors in melanoma spheres and tumour xenografts regulate the NOTCH pathway

The use of adherent monolayer cultures have produced many insights into melanoma cell growth and differentiation, but often novel therapeutics demonstrated to act on these cells are not active in vivo. It is imperative that new methods of growing melanoma cells that reflect growth in vivo are investigated. To this end, a range of human melanoma cell lines passaged as adherent cultures or induced to form melanoma spheres (melanospheres) in stem cell media have been studied to compare cellular characteristics and protein expression. Melanoma spheres and tumours grown from cell lines as mouse xenografts had increased heterogeneity when compared with adherent cells and 3D-spheroids in agar (aggregates). Furthermore, cells within the melanoma spheres and mouse xenografts each displayed a high level of reciprocal BRN2 or MITF expression, which matched more closely the pattern seen in human melanoma tumours in situ, rather than the propensity for co-expression of these important melanocytic transcription factors seen in adherent cells and 3D-spheroids. Notably, when the levels of the BRN2 and MITF proteins were each independently repressed using siRNA treatment of adherent melanoma cells, members of the NOTCH pathway responded by decreasing or increasing expression, respectively. This links BRN2 as an activator, and conversely, MITF as a repressor of the NOTCH pathway in melanoma cells. Loss of the BRN2-MITF axis in antisense-ablated cell lines decreased the melanoma sphere-forming capability, cell adhesion during 3D-spheroid formation and invasion through a collagen matrix. Combined, this evidence suggests that the melanoma sphere-culture system induces subpopulations of cells that may more accurately portray the in vivo disease, than the growth as adherent melanoma cells.

Upregulated ankyrin repeat-rich membrane spanning protein contributes to tumour progression in cutaneous melanoma

BACKGROUND

We have previously demonstrated that overexpression of ankyrin repeat-rich membrane spanning (ARMS) protein facilitates melanoma formation via conferring apoptotic resistance. This study aims to investigate whether ARMS contributes to melanoma progression.

METHOD

Using immunohistochemistry, we graded the expression level of ARMS in 54 cases of primary melanoma and 46 cases of metastatic melanoma. The immunointensity of ARMS was statistically correlated with individual clinicopathological characteristics. By RNA interference, stable melanoma cell clones with ARMS-knockdown were constructed, and were used for in vitro scratch wound, transwell invasion assays, and in vivo lung metastasis experiment.

RESULTS

Stronger immunointensity of ARMS was observed mostly in melanomas with Breslow tumour thickness >1.0  mm (Fisher's exact test, P=0.002) or with nodal metastasis (Fisher's exact test, P=0.026), and was correlated with a worse overall survival in melanoma patients (log-rank test, P=0.04). Depletion of ARMS inhibited migration, invasion, and metastatic potential of melanoma cells in vitro and in vivo. Moreover, ARMS mediated melanoma cell migration and invasion through activation of the extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK signalling pathway.

CONCLUSION

Ankyrin repeat-rich membrane spanning expression, conjunctly with tumour thickness or ulceration, may serve as a prognostic factor in patients with cutaneous melanoma.

Uncovering the role of hypoxia inducible factor-1α in skin carcinogenesis

The hypoxia inducible factor-1α (HIF-1α) is a pleiotropic transcription factor typically activated in response to low oxygen tension as well as other stress factors in normoxic conditions. Upon activation HIF-1α mediates the transcriptional activation of target genes involved in a variety of processes comprising stress adaptation, metabolism, growth and invasion, but also apoptotic cell death. The molecular mechanisms, signaling pathways and downstream targets evoked by the activation of HIF-1α in epidermal cells are becoming increasingly understood and underscore the participation of HIF-1α in crucial processes including malignant transformation and cancer progression. Recent studies have implicated HIF-1α as an integral part of the multifaceted signal transduction initiated by the exposure of keratinocytes to ultraviolet radiation B (UVB), which represents the most ubiquitous hazard for human skin and the principal risk factor for skin cancer. HIF-1α activation by UVB exposure contributes to either repair or the removal of UVB-damaged keratinocytes by inducing apoptosis, thus revealing a tumor suppressor role for HIF-1α in these cells. On the other hand, the constitutive expression of HIF-1α evoked by the mild hypoxic state of the skin has been implicated as a positive factor in the transformation of normal melanocytes into malignant melanoma, one of the most aggressive types of human cancers. Here we review the uncovered and complex role of HIF-1α in skin carcinogenesis.

Keratinocytes drive melanoma invasion in a reconstructed skin model

Melanoma progression is a multistep progression from a common melanocytic nevus through the radial growth phase, the invasive vertical growth phase finally leading to metastatic spread into distant organs. Migration and invasion of tumor cells requires secretion of proteases to facilitate remodeling of the extracellular matrix including basement membranes. Here we used a reconstructed skin model to investigate melanoma growth and invasion in vitro. Using this model we show that the dermoepidermal basement membrane prevents the invasion of metastatic melanoma BLM and MV3 cells in the absence of a stratified epidermis. In the reconstructed skin model, matrix metalloproteinase-9, a protease activated early in melanoma development, is secreted by the keratinocytes and subsequently activated by an unknown soluble factor secreted by the melanoma cells. The dynamic interplay between keratinocytes and melanoma cells is further shown by an altered growth pattern of melanoma cells and the finding that a reconstructed epidermis induces invasion. Overall, our findings show that the invasive behavior of melanoma cells is determined by the melanoma cells themselves, but that the interplay between surrounding keratinocytes and the melanoma cells plays an important role in melanoma invasion.

Glycans in melanoma screening. Part 1. The role of β1,6-branched N-linked oligosaccharides in melanoma

Melanoma, which is one of the most aggressive human tumours, originates from melanin-producing melanocytes. As no effective systemic therapy exists for advanced-stage melanoma, the best chance of recovery remains surgical removal of thin early-stage melanoma. Aberrant glycosylation is a hallmark of malignancy and a well-studied class of β1,6-branched oligosaccharides is associated with malignant transformation of rodent and human cells, and poor prognosis in cancer patients. It is evident that increased β1,6 branching significantly contributes to the phenotype of melanoma cells, influencing the adhesion to extracellular matrix components and motility as well as invasive and metastatic potential. Despite the considerable success in establishing the role of β1,6-branched N-linked oligosaccharides in melanoma biology, there is virtually no progress in using these glycans as a screening tool for the early diagnosis of the disease, or a target-specific therapeutic agent.

Molecular pathogenesis of sporadic melanoma and melanoma-initiating cells

Recent advances in molecular genetics and cancer stem cell biology have shed some light on the molecular basis of melanomagenesis. In this review, we will focus on major genetic alterations in the melanoma, particularly pathways involved in cell proliferation, apoptosis, and tumor suppression. The potential role of melanoma-initiating cells during melanomagenesis and progression will also be discussed. Understanding pathogenesis of melanoma may uncover new diagnostic clues and therapeutic targets for this increasingly prevalent disease.

Atypical mole syndrome and dysplastic nevi: identification of populations at risk for developing melanoma - review article

Atypical Mole Syndrome is the most important phenotypic risk factor for developing cutaneous melanoma, a malignancy that accounts for about 80% of deaths from skin cancer. Because the diagnosis of melanoma at an early stage is of great prognostic relevance, the identification of Atypical Mole Syndrome carriers is essential, as well as the creation of recommended preventative measures that must be taken by these patients.

Targeted therapy for melanoma: a primer

Melanoma is the most aggressive form of skin cancer. Unfortunately, despite recent improvements for some solid tumors, the prevalence and mortality of melanoma continue to increase. The identification of activating mutations in melanoma, combined with a growing appreciation of the different pattern of genetic changes in the anatomically defined melanoma subtypes, has become the focus of a concerted effort to translate these discoveries into personalized therapeutic approaches for this disease. This article reviews the known mutations, amplifications, and deletions in kinase signaling pathways that have been implicated in melanoma; the prevalence of these genetic events in clinicopathologically defined melanoma subtypes; and the results of clinical trials that use targeted therapy approaches to block aberrantly activated pathways resulting from these mutations. The challenges that must be overcome to achieve improved outcomes with targeted therapies in melanoma in the future are also discussed.

Decoding melanoma metastasis

Metastasis accounts for the vast majority of morbidity and mortality associated with melanoma. Evidence suggests melanoma has a predilection for metastasis to particular organs. Experimental analyses have begun to shed light on the mechanisms regulating melanoma metastasis and organ specificity, but these analyses are complicated by observations of metastatic dormancy and dissemination of melanocytes that are not yet fully malignant. Additionally, tumor extrinsic factors in the microenvironment, both at the site of the primary tumor and the site of metastasis, play important roles in mediating the metastatic process. As metastasis research moves forward, paradigms explaining melanoma metastasis as a step-wise process must also reflect the temporal complexity and heterogeneity in progression of this disease. Genetic drivers of melanoma as well as extrinsic regulators of disease spread, particularly those that mediate metastasis to specific organs, must also be incorporated into newer models of melanoma metastasis.

Prognostic significance of RUNX3 expression in human melanoma

BACKGROUND

RUNX3 is a tumor suppressor that plays important roles in cell proliferation, apoptosis, and metastasis. The authors investigated the role of RUNX3 in melanoma pathogenesis and analyzed the prognostic impact of RUNX3 expression in a large series of melanoma patients.

METHODS

Two sets of tissue microarrays were constructed, including 440 cases of melanomas (202 for the training set and 238 for the validation set) and 88 cases of nevi (25 normal nevi and 63 dysplastic nevi). RUNX3 expression was evaluated by immunohistochemistry.

RESULTS

Positive RUNX3 expression was observed in 56%, 54%, 33%, and 24% of the biopsies in normal nevi, dysplastic nevi, primary melanoma, and melanoma metastases, respectively. Significant differences for positive nuclear RUNX3 staining were observed between dysplastic nevi and primary melanomas (P = .002, chi-square test), between dysplastic nevi and melanoma metastases (P < .001, chi-square test), and between primary melanoma and melanoma metastases (P = .045, chi-square test). Loss of RUNX3 expression was correlated with a worse 5-year survival of melanoma patients in both training and validation sets. Furthermore, loss of RUNX3 expression was also correlated with a poor 5-year disease-specific survival in primary melanoma (P = .001) and metastatic melanoma patients (P = .008). Multivariate Cox regression analysis revealed that positive RUNX3 expression is an independent prognostic factor to predict melanoma patient outcome.

CONCLUSIONS

Our findings indicate that RUNX3 plays an important role in melanoma pathogenesis and may serve as a promising prognostic marker for melanoma.

Combating melanoma: the use of photodynamic therapy as a novel, adjuvant therapeutic tool

Metastatic malignant melanoma remains one of the most dreaded skin cancers worldwide. Numerous factors contribute to its resistance to hosts of treatment regimes and despite significant scientific advances over the last decade in the field of chemotherapeutics and melanocytic targets, there still remains the need for improved therapeutic modalities. Photodynamic therapy, a minimally invasive therapeutic modality has been shown to be effective in a number of oncologic and non-oncologic conditions. Using second-generation stable, lipophilic photosensitizers with optimised wavelengths, PDT may be a promising tool for adjuvant therapy in combating melanoma. Potential targets for PDT in melanoma eradication include cell proliferation inhibition, activation of cell death and reduction in pro-survival autophagy and a decrease in the cellular melanocytic antioxidant system. This review highlights the current knowledge with respect to these characteristics and suggests that PDT be considered as a good candidate for adjuvant treatment in post-resected malignant metastatic melanoma. Furthermore, it suggests that primary consideration must be given to organelle-specific destruction in melanoma specifically targeting the melanosomes - the one organelle that is specific to cells of the melanocytic lineage that houses the toxic compound, melanin. We believe that using this combined knowledge may eventually lead to an effective therapeutic tool to combat this highly intractable disease.

Molecular Pathogenesis of Sporadic Melanoma and Melanoma-Initiating Cells

Recent advances in molecular genetics and cancer stem cell biology have shed some light on the molecular basis of melanomagenesis. In this review, we will focus on major genetic alterations in the melanoma, particularly pathways involved in cell proliferation, apoptosis, and tumor suppression. The potential role of melanoma-initiating cells during melanomagenesis and progression will also be discussed. Understanding pathogenesis of melanoma may uncover new diagnostic clues and therapeutic targets for this increasingly prevalent disease.

MITF-siRNA formulation is a safe and effective therapy for human melasma

It is unclear whether siRNA-based agents can be a safe and effective therapy for diseases. In this study, we demonstrate that microphthalmia-associated transcription factor-siRNA (MITF-siR)-silenced MITF gene expression effectively induced a significant reduction in tyrosinase (TYR), tyrosinase-related protein 1, and melanocortin 1 receptor (MC1R) levels. The siRNAs caused obvious inhibition of melanin synthesis and melanoma cell apoptosis. Using a novel type of transdermal peptide, we developed the formulation of an MITF-siR cream. Results demonstrated that hyperpigmented facial lesions of siRNA-treated subjects were significantly lighter after 12 weeks of therapy than before treatment (P < 0.001); overall improvement was first noted after 4 weeks of siRNA treatment. At the end of treatment, clinical and colorimetric evaluations demonstrated a 90.4% lightening of the siRNA-treated lesions toward normal skin color. The relative melanin contents in the lesions and adjacent normal skin were decreased by 26% and 7.4%, respectively, after treatment with the MITF-siR formulation. Topical application of siRNA formulation significantly lightens brown facial hypermelanosis and lightens normal skin in Asian individuals. This treatment represents a safe and effective therapy for melasma, suggesting that siRNA-based agents could be developed for treating other diseases such as melanoma.

Methods of detection of circulating melanoma cells: a comparative overview

Disease dissemination is the major cause of melanoma-related death. A crucial step in the metastatic process is the intravascular invasion and circulation of melanoma cells in the bloodstream with subsequent development of distant micrometastases that is initially clinically undetectable and will eventually progress into clinically apparent metastasis. Therefore, the use of molecular methods to detect circulating melanoma cells may be of value in risk stratification and clinical management of such patients. Herein, we review the currently applied techniques for the detection, isolation, enrichment and further characterization of circulating melanoma cells from peripheral blood samples in melanoma patients. Furthermore, we provide a brief overview of the various molecular markers currently being evaluated as prognostic indicators of melanoma progression.

The p53/p21Cip1/ Waf1 pathway mediates the effects of SPARC on melanoma cell cycle progression

Secreted protein acidic and rich in cysteine (SPARC), or osteonectin, belongs to the family of matricellular proteins that modulate cell-matrix interactions and cellular functions. SPARC is highly expressed in melanoma, and we reported that SPARC promotes epithelial/mesenchymal-like changes and cell migration. Here, we used siRNA and conditional shRNA to investigate the contribution of tumor-derived SPARC to melanoma cell growth in vitro and in vivo. We found that depletion of SPARC induces G2/M cell cycle arrest and tumor growth inhibition with activation of p53 and induction of p21(Cip1/Waf1) acting as a checkpoint, preventing efficient mitotic progression. In addition, we demonstrate that reduced mesenchymal features and the invasive potential of SPARC-silenced cells are independent of p21(Cip1/Waf1) induction and cell cycle arrest. Importantly, overexpression of SPARC reduces p53 protein levels and leads to an increase in cell number during exponential growth. Our findings indicate that in addition to its well-known function as a mediator of melanoma cell migration and tumor-host interactions, SPARC regulates, in a cell-autonomous manner, cell cycle progression and proliferation through the p53/p21(Cip1/Waf1) pathway.

Gene expression profiles of human melanoma cells with different invasive potential reveal TSPAN8 as a novel mediator of invasion

Background:

Metastatic melanoma requires early detection, being treatment resistant. However, the earliest events of melanoma metastasis, and especially of dermal invasion, remain ill defined.

Results and methods:

Gene expression profiles of two clonal subpopulations, selected from the same human melanoma cell line, but differing in ability to cross the dermal–epidermal junction in skin reconstructs, were compared by oligonucleotide microarray. Of 26 496 cDNA probes, 461 were differentially expressed (>2-fold; P< 0.001), only 71 genes being upregulated in invasive cells. Among them, TSPAN8, a tetraspanin not yet described in melanoma, was upregulated at mRNA and protein levels in melanoma cells from the invasive clone, as assessed by RT–PCR, flow cytometry and western blot analysis. Interestingly, TSPAN8 was the only tetraspanin in which overexpression correlated with invasive phenotype. Flow cytometry of well-defined melanoma cell lines confirmed that TSPAN8 was exclusively expressed by invasive, but not non-invasive melanoma cells or normal melanocytes. Immunohistochemistry revealed that TSPAN8 was expressed by melanoma cells in primary melanomas and metastases, but not epidermal cells in healthy skin. The functional role of TSPAN8 was demonstrated by silencing endogenous TSPAN8 with siRNA, reducing invasive outgrowth from tumour spheroids within matrigel without affecting cell proliferation or survival.

Conclusion:

TSPAN8 expression may enable melanoma cells to cross the cutaneous basement membrane, leading to dermal invasion and progression to metastasis. TSPAN8 could be a promising target in early detection and treatment of melanoma.

A new era: melanoma genetics and therapeutics

We have recently witnessed an explosion in our understanding of melanoma. Knowledge of the molecular basis of melanoma and the successes of targeted therapies have pushed melanoma care to the precipice of a new era. Identification of significant pathways and oncogenes has translated to the development of targeted therapies, some of which have produced major clinical responses. In this review, we provide an overview of selected key pathways and melanoma oncogenes as well as the targeted agents and therapeutic approaches whose successes suggest the promise of a new era in melanoma and cancer therapy. Despite these advances, the conversion of transient remissions to stable cures remains a vital challenge. Continued progress towards a better understanding about the complexity and redundancy responsible for melanoma progression may provide direction for anti-cancer drug development.

Aberrant DNA methylation in malignant melanoma

Malignant melanoma remains one of the most deadly human cancers with no effective cures for metastatic disease. The poor efficacy of current therapy in advanced melanoma highlights the need for better understanding of molecular mechanisms contributing to the disease. Recent work has shown that epigenetic changes, including aberrant DNA methylation, lead to alterations in gene expression and are as important in the development of malignant melanoma as the specific and well-characterized genetic events. Reversion of these methylation patterns could thus lead to a more targeted therapy and are currently under clinical investigation. The purpose of this review is to compile recent information on aberrant DNA methylation of melanoma, to highlight key genes and molecular pathways in melanoma development, which have been found to be epigenetically altered and to provide insight as to how DNA methylation might serve as targeted treatment option as well as a molecular and prognostic marker in malignant melanoma.

The immunohistochemistry of invasive and proliferative phenotype switching in melanoma: a case report

To date there is no effective therapy for metastatic melanoma and at the molecular level the disease progression is poorly understood. A recent study by our group led to the development of a novel phenotype switching model for melanoma progression, wherein cells transition back-and-forth between states of proliferation and invasion to drive disease progression. To explore the model's clinical relevance we interrogated phenotype-specific expression patterns in human melanoma patient material. A matched primary/metastasis pair from a human melanoma patient was obtained and immunohistochemically stained for proliferative and invasive phenotype markers. These were also stained for hypoxia and blood vessel markers. Proliferative phenotype markers Melan-A and Mitf showed consistent anti-correlation with invasive phenotype marker Wnt5A and hypoxia marker Glut-1. These also correlated with observed intra-tumoural vascularization patterns. Similar pattern distributions were present in both primary and metastasis samples. Strikingly, we observed that late phase metastatic melanoma cells adopt morphologies and behaviours identical to very early phase cells. The expression patterns observed closely matched expectations derived from previous in vitro and xenografting experiments. These results highlight the likelihood that disease progression involves melanoma cells retaining the capacity to regulate the expression of metastatic potential critical factors according to changing microenvironmental conditions.

Role of interferon {alpha} (IFN{alpha})-inducible Schlafen-5 in regulation of anchorage-independent growth and invasion of malignant melanoma cells

IFNα exerts potent inhibitory activities against malignant melanoma cells in vitro and in vivo, but the mechanisms by which it generates its antitumor effects remain unknown. We examined the effects of interferon α (IFNα) on the expression of human members of the Schlafen (SLFN) family of genes, a group of cell cycle regulators that mediate growth-inhibitory responses. Using quantitative RT-real time PCR, we found detectable basal expression of all the different human SLFN genes examined (SLFN5, SLFN11, SLFN12, SLFN13, and SLFN14), in malignant melanoma cells and primary normal human melanocytes, but SLFN5 basal expression was suppressed in all analyzed melanoma cell lines. Treatment of melanoma cells with IFNα resulted in induction of expression of SLFN5 in malignant cells, suggesting a potential involvement of this gene in the antitumor effects of IFNα. Importantly, stable knockdown of SLFN5 in malignant melanoma cells resulted in increased anchorage-independent growth, as evidenced by enhanced colony formation in soft agar assays. Moreover, SLFN5 knockdown also resulted in increased invasion in three-dimensional collagen, suggesting a dual role for SLFN5 in the regulation of invasion and anchorage-independent growth of melanoma cells. Altogether, our findings suggest an important role for the SLFN family of proteins in the generation of the anti-melanoma effects of IFNα and for the first time directly implicate a member of the human SLFN family in the regulation of cell invasion.

Prognostic significance of Sox4 expression in human cutaneous melanoma and its role in cell migration and invasion

The Sox4 transcription factor is involved in various cellular processes, such as embryonic development and differentiation. Deregulated expression of Sox4 in several human cancers has been reported to date, but its role in melanoma is unknown. We explored the role of Sox4 in melanoma pathogenesis in vivo and in vitro. Using tissue microarray, we evaluated Sox4 expression in 180 melanocytic lesions and investigated its role in melanoma cell migration and invasion. Sox4 expression was remarkably reduced in metastatic melanoma compared with dysplastic nevi (P < 0.05) and primary melanoma (P < 0.01). This reduction was correlated with a poorer disease-specific survival of melanoma patients (P = 0.039). Multivariate Cox regression analysis revealed that reduced Sox4 expression is an independent prognostic factor (P = 0.049). Knockdown of Sox4 enhanced melanoma cell invasion, migration, and stress fiber formation. The increased migration and invasion on Sox4 knockdown depends on the presence of nuclear factor (NF)-κB p50 and is abrogated when p50 is knocked down. We further observed inhibition of NF-κB p50 transcription by Sox4, in addition to a reverse pattern of expression of Sox4 and NF-κB p50 in different stages of melanocytic lesions. Our results suggest that Sox4 regulates melanoma cell migration and invasion in an NF-κB p50-dependent manner and may serve as a prognostic marker and potential therapeutic target for human melanoma.

siRNA knockdown of ribonucleotide reductase inhibits melanoma cell line proliferation alone or synergistically with temozolomide

Systemically delivered small interfering RNA (siRNA) therapies for cancer have begun clinical development. The effects of siRNA-mediated knockdown of ribonucleotide reductase subunit-2 (RRM2), a rate-limiting enzyme in cell replication, were investigated in malignant melanoma, a cancer with a paucity of effective treatment options. A panel of human melanoma cell lines was transfected with siRNA to induce the knockdown of RRM2. Sequence-specific, siRNA-mediated inhibition of RRM2 effectively blocked cell proliferation and induced G1/S-phase cell cycle arrest. This effect was independent of the activating oncogenic mutations in the tested cell lines. Synergistic inhibition of melanoma cell proliferation was achieved using the combination of siRNA targeting RRM2 and temozolomide, an analog of the current standard of care for melanoma chemotherapy. In conclusion, siRNA-mediated RRM2 knockdown significantly inhibits proliferation of melanoma cell lines with different oncogenic mutations with synergistic enhancement in combination with temozolomide.

Activation of c-Jun N-terminal kinase is essential for mitochondrial membrane potential change and apoptosis induced by doxycycline in melanoma cells

BACKGROUND AND PURPOSE

Tetracyclines were recently found to induce tumour cell death, but the early processes involved in this cytotoxic effect remain unclear.

EXPERIMENTAL APPROACH

Viability of human and mouse melanoma cells was determined by MTT assay and flow cytometry. Kinase/protein/caspase activation was measured by Western blotting and mitochondrial membrane potential (DeltaPsi(m)) was analyzed by fluorescence microscopy and flow cytometry.

KEY RESULTS

Human and mouse melanoma cells were treated with doxycycline or minocycline but only doxycycline was cytotoxic. This cell death (apoptosis) in A2058 cells involved activation of caspase-3, -7 and -9 and contributed to inhibition, by doxycycline, of matrix metalloproteinase (MMP) activity and migration of these cells. Doxycycline induced intra-cellular reactive oxygen species (ROS) production, apoptosis signal-regulated kinase 1 (ASK1), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) activation at an early stage of treatment and induced mitochondrial cytochrome c release into cytosol and DeltaPsi(m) change during apoptosis. The JNK inhibitor/small interference RNA inhibited doxycycline-induced JNK activation, DeltaPsi(m) change and apoptosis, but did not affect ASK1 activation, suggesting a role of ASK1 for JNK activation in melanoma cell apoptosis. Two ROS scavengers reduced doxycycline-induced JNK and caspase activation, and apoptosis. Taken together, the results suggest the involvement of a ROS-ASK1-JNK pathway in doxycycline-induced melanoma cell apoptosis.

CONCLUSIONS AND IMPLICATIONS

We have shown a promising cytotoxic effect of doxycycline on melanoma cells, have identified ROS and ASK1 as the possible initiators and have demonstrated that JNK activation is necessary for doxycycline-induced melanoma cell apoptosis.

Anti-melanoma efficacy of internal radionuclide therapy in relation to melanin target distribution

Targeted internal radionuclide therapy (TRT) could be an efficient, specific way to treat disseminated melanoma. Based on a previous pharmacomodulation study, we selected a quinoxaline-derived molecule (ICF01012) for its melanin specificity and kinetic properties suitable for TRT. Here, we determined the efficacy of [(131)I]ICF01012 radiotherapy in vitro and in vivo in relation to melanogenesis using human melanoma models. [(125)I]ICF01012 uptake was first assessed in relation to melanin content. We found that melanin distribution in different models was representative of pathology seen in human tumours: melanin content was high in the extracellular space of SKMel3 tumours, and accumulated primarily in melanophages in M4Beu tumours. Targeted [(131)I]ICF01012 radiotherapy had a strong anti-tumoural efficacy in pigmented versus unpigmented tumours, regardless of target distribution and content. This study supports the use of melanin targeting with (131)I-labelled iodoquinoxaline for effective treatment of melanoma.

Melanoma staging: facts and controversies

The value of staging examinations remains controversial for the initial staging in melanoma patients at the time of the primary diagnosis and for surveillance. Issues concerning tumor recurrences and progression must be discussed separately for different risk groups. For low-risk patients (stage IA; tumor thickness less than 1 mm), staging examinations like sentinel lymph node biopsy (SLNB), blood tests, or imaging can generally be abandoned. Baseline staging with simple techniques is at the discretion of the physician. In intermediate-risk patients (stages IB and IIA), an initial staging examination involving SLNB and computed tomography (CT) scans is recommended. Further follow-up may be restricted to physical examinations, blood tests of tumor marker protein S100beta, and to lymph node ultrasonography. If findings are suspicious, further imaging procedures may be involved. In high-risk patients (stages IIB to III), an initial staging examination with CT is recommended, and regular follow-up every 6 months with whole body imaging by CT or magnetic resonance imaging seems useful. Physical examinations, blood tests of tumor marker protein S100beta, and lymph node ultrasound imaging should be routine. This intense follow-up may enable surgical treatments with complete removal of all recognizable metastases in about 15% to 25% of patients and improve their prognosis. The risk of recurrence or tumor progression is very high in stage IV patients, and their management is individualized.

Survivin enhances motility of melanoma cells by supporting Akt activation and {alpha}5 integrin upregulation

Survivin expression in melanoma is inversely correlated with patient survival. Transgenic mice harboring melanocyte-specific overexpression of survivin exhibit increased susceptibility to UV-induced melanoma and metastatic progression. To understand the mechanistic basis for metastatic progression, we investigated the effects of survivin on the motility of human melanocytes and melanoma cells. We found that survivin overexpression enhanced migration on fibronectin and invasion through Matrigel, whereas survivin knockdown under subapoptotic conditions blocked migration and invasion. In melanocytes, survivin overexpression activated the Akt and mitogen-activated protein kinase pathways. Akt phosphorylation was required for survivin-enhanced migration and invasion, whereas Erk phosphorylation was required only for enhanced invasion. In both melanocytes and melanoma cells, survivin overexpression was associated with upregulation of α5 integrin (fibronectin receptor component), the antibody-mediated blockade or RNA interference-mediated knockdown of which blocked survivin-enhanced migration. Knockdown of α5 integrin did not affect Akt activation, but inhibition of Akt phosphorylation prevented α5 integrin upregulation elicited by survivin overexpression. Together, our results showed that survivin enhanced the migration and invasion of melanocytic cells and suggested that survivin may promote melanoma metastasis by supporting Akt-dependent upregulation of α5 integrin.

CREB inhibits AP-2alpha expression to regulate the malignant phenotype of melanoma

BACKGROUND

The loss of AP-2alpha and increased activity of cAMP-responsive element binding (CREB) protein are two hallmarks of malignant progression of cutaneous melanoma. However, the molecular mechanism responsible for the loss of AP-2alpha during melanoma progression remains unknown.

METHODOLOGY/PRINCIPAL FINDINGS

Herein, we demonstrate that both inhibition of PKA-dependent CREB phosphorylation, as well as silencing of CREB expression by shRNA, restored AP-2alpha protein expression in two metastatic melanoma cell lines. Moreover, rescue of CREB expression in CREB-silenced cell lines downregulates expression of AP-2alpha. Loss of AP-2alpha expression in metastatic melanoma occurs via a dual mechanism involving binding of CREB to the AP-2alpha promoter and CREB-induced overexpression of another oncogenic transcription factor, E2F-1. Upregulation of AP-2alpha expression following CREB silencing increases endogenous p21(Waf1) and decreases MCAM/MUC18, both known to be downstream target genes of AP-2alpha involved in melanoma progression.

CONCLUSIONS/SIGNIFICANCE

Since AP-2alpha regulates several genes associated with the metastatic potential of melanoma including c-KIT, VEGF, PAR-1, MCAM/MUC18, and p21(Waf1), our data identified CREB as a major regulator of the malignant melanoma phenotype.

The role of phytonutrients in skin health

Photodamage is known to occur in skin with exposure to sunlight, specifically ultraviolet (UV) radiation. Such damage includes inflammation, oxidative stress, breakdown of the extracellular matrix, and development of cancer in the skin. Sun exposure is considered to be one of the most important risk factors for both nonmelanoma and melanoma skin cancers. Many phytonutrients have shown promise as photoprotectants in clinical, animal and cell culture studies. In part, the actions of these phytonutrients are thought to be through their actions as antioxidants. In regard to skin health, phytonutrients of interest include vitamin E, certain flavonoids, and the carotenoids, β-carotene, lycopene and lutein.

Specific targeting of Wnt/β-catenin signaling in human melanoma cells by a dietary triterpene lupeol

Wingless (Wnt) signaling pathway regulates a variety of cellular processes including proliferation, differentiation, survival, apoptosis and cell motility. Aberrant activation of Wnt/β-catenin pathway has been observed in approximately one-third of melanomas and this subset has very poor prognosis suggesting that targeting Wnt signaling could be a promising strategy against this subtype. Mel 928 and Mel 1241 melanoma cells representative of cells with constitutive activation of Wnt/β-catenin signaling pathway and Mel 1011 representative of cells that lack this pathway were treated with a dietary triterpene lupeol and its effects on growth, proliferation, β-catenin transcriptional activity and Wnt target genes were determined both in vitro and in vivo. Lupeol treatment to Mel 928 and Mel 1241 but not Mel 1011 cells resulted in a dose-dependent (i) decrease in cell viability, (ii) induction of apoptosis, (iii) decrease in colonogenic potential, (iv) decrease in β-catenin transcriptional activity and (v) decrease in the expression of Wnt target genes. Most importantly, lupeol restricted the translocation of β-catenin from the cytoplasm to the nucleus. Lupeol also decreased the growth of Mel 928 but not Mel 1011-derived tumors implanted in the athymic nude mice. The decrease in Mel 928-derived tumor growth was associated with a decrease in the expression of Wnt target genes c-myc, cyclin D1, proliferation markers proliferating cell nuclear antigen and Ki-67 and invasion marker osteopontin. We suggest that lupeol alone or as an adjuvant to current therapies could be developed as an agent for the management of human melanomas harboring constitutive Wnt/β-catenin signaling.

Environmental and genetic activation of a brain-adipocyte BDNF/leptin axis causes cancer remission and inhibition

Cancer is influenced by its microenvironment, yet broader, environmental effects also play a role but remain poorly defined. We report here that mice living in an enriched housing environment show reduced tumor growth and increased remission. We found this effect in melanoma and colon cancer models, and that it was not caused by physical activity alone. Serum from animals held in an enriched environment (EE) inhibited cancer proliferation in vitro and was markedly lower in leptin. Hypothalamic brain-derived neurotrophic factor (BDNF) was selectively upregulated by EE, and its genetic overexpression reduced tumor burden, whereas BDNF knockdown blocked the effect of EE. Mechanistically, we show that hypothalamic BDNF downregulated leptin production in adipocytes via sympathoneural beta-adrenergic signaling. These results suggest that genetic or environmental activation of this BDNF/leptin axis may have therapeutic significance for cancer.

GLI2-mediated melanoma invasion and metastasis

BACKGROUND

The transforming growth factor-beta (TGF-beta) pathway, which has both tumor suppressor and pro-oncogenic activities, is often constitutively active in melanoma and is a marker of poor prognosis. Recently, we identified GLI2, a mediator of the hedgehog pathway, as a transcriptional target of TGF-beta signaling.

METHODS

We used real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blotting to determine GLI2 expression in human melanoma cell lines and subsequently classified them as GLI2high or as GLI2low according to their relative GLI2 mRNA and protein expression levels. GLI2 expression was reduced in a GLI2high cell line with lentiviral expression of short hairpin RNA targeting GLI2. We assessed the role of GLI2 in melanoma cell invasiveness in Matrigel assays. We measured secretion of matrix metalloproteinase (MMP)-2 and MMP-9 by gelatin zymography and expression of E-cadherin by western blotting and RT-PCR. The role of GLI2 in development of bone metastases was determined following intracardiac injection of melanoma cells in immunocompromised mice (n = 5-13). Human melanoma samples (n = 79) at various stages of disease progression were analyzed for GLI2 and E-cadherin expression by immunohistochemistry, in situ hybridization, or RT-PCR. All statistical tests were two-sided.

RESULTS

Among melanoma cell lines, increased GLI2 expression was associated with loss of E-cadherin expression and with increased capacity to invade Matrigel and to form bone metastases in mice (mean osteolytic tumor area: GLI2high vs GLI2low, 2.81 vs 0.93 mm(2), difference = 1.88 mm(2), 95% confidence interval [CI] = 1.16 to 2.60, P < .001). Reduction of GLI2 expression in melanoma cells that had expressed high levels of GLI2 substantially inhibited both basal and TGF-beta-induced cell migration, invasion (mean number of Matrigel invading cells: shGLI2 vs shCtrl (control), 52.6 vs 100, difference = 47.4, 95% CI = 37.0 to 57.8, P = .024; for shGLI2 + TGF-beta vs shCtrl + TGF-beta, 31.0 vs 161.9, difference = -130.9, 95% CI = -96.2 to -165.5, P = .002), and MMP secretion in vitro and the development of experimental bone metastases in mice. Within human melanoma lesions, GLI2 expression was heterogeneous, associated with tumor regions in which E-cadherin was lost and increased in the most aggressive tumors.

CONCLUSION

GLI2 was directly involved in driving melanoma invasion and metastasis in this preclinical study.

GLI2-mediated melanoma invasion and metastasis

BACKGROUND

The transforming growth factor-beta (TGF-beta) pathway, which has both tumor suppressor and pro-oncogenic activities, is often constitutively active in melanoma and is a marker of poor prognosis. Recently, we identified GLI2, a mediator of the hedgehog pathway, as a transcriptional target of TGF-beta signaling.

METHODS

We used real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blotting to determine GLI2 expression in human melanoma cell lines and subsequently classified them as GLI2high or as GLI2low according to their relative GLI2 mRNA and protein expression levels. GLI2 expression was reduced in a GLI2high cell line with lentiviral expression of short hairpin RNA targeting GLI2. We assessed the role of GLI2 in melanoma cell invasiveness in Matrigel assays. We measured secretion of matrix metalloproteinase (MMP)-2 and MMP-9 by gelatin zymography and expression of E-cadherin by western blotting and RT-PCR. The role of GLI2 in development of bone metastases was determined following intracardiac injection of melanoma cells in immunocompromised mice (n = 5-13). Human melanoma samples (n = 79) at various stages of disease progression were analyzed for GLI2 and E-cadherin expression by immunohistochemistry, in situ hybridization, or RT-PCR. All statistical tests were two-sided.

RESULTS

Among melanoma cell lines, increased GLI2 expression was associated with loss of E-cadherin expression and with increased capacity to invade Matrigel and to form bone metastases in mice (mean osteolytic tumor area: GLI2high vs GLI2low, 2.81 vs 0.93 mm(2), difference = 1.88 mm(2), 95% confidence interval [CI] = 1.16 to 2.60, P < .001). Reduction of GLI2 expression in melanoma cells that had expressed high levels of GLI2 substantially inhibited both basal and TGF-beta-induced cell migration, invasion (mean number of Matrigel invading cells: shGLI2 vs shCtrl (control), 52.6 vs 100, difference = 47.4, 95% CI = 37.0 to 57.8, P = .024; for shGLI2 + TGF-beta vs shCtrl + TGF-beta, 31.0 vs 161.9, difference = -130.9, 95% CI = -96.2 to -165.5, P = .002), and MMP secretion in vitro and the development of experimental bone metastases in mice. Within human melanoma lesions, GLI2 expression was heterogeneous, associated with tumor regions in which E-cadherin was lost and increased in the most aggressive tumors.

CONCLUSION

GLI2 was directly involved in driving melanoma invasion and metastasis in this preclinical study.

Pro-prion binds filamin A, facilitating its interaction with integrin beta1, and contributes to melanomagenesis

Filamin A (FLNA) is an integrator of cell mechanics and signaling. The spreading and migration observed in FLNA sufficient A7 melanoma cells but not in the parental FLNA deficient M2 cells have been attributed to FLNA. In A7 and M2 cells, the normal prion (PrP) exists as pro-PrP, retaining its glycosylphosphatidyl-inositol (GPI) anchor peptide signal sequence (GPI-PSS). The GPI-PSS of PrP has a FLNA binding motif and binds FLNA. Reducing PrP expression in A7 cells alters the spatial distribution of FLNA and organization of actin and diminishes cell spreading and migration. Integrin β1 also binds FLNA. In A7 cells, FLNA, PrP, and integrin β1 exist as two independent, yet functionally linked, complexes; they are FLNA with PrP or FLNA with integrin β1. Reducing PrP expression in A7 cells decreases the amount of integrin β1 bound to FLNA. A PrP GPI-PSS synthetic peptide that crosses the cell membrane inhibits A7 cell spreading and migration. Thus, in A7 cells FLNA does not act alone; the binding of pro-PrP enhances association between FLNA and integrin β1, which then promotes cell spreading and migration. Pro-PrP is detected in melanoma in situ but not in melanocyte. Invasive melanoma has more pro-PrP. The binding of pro-PrP to FLNA, therefore, contributes to melanomagenesis.

Inhibitory effects of Lang-du extract on the in vitro and in vivo growth of melanoma cells and its molecular mechanisms of action

The purpose of this study is to investigate the effects of Lang-du extract (LDE) from Traditional Chinese Medicine (TCM) Euphorbia fischeriana Steud on the in vitro and in vivo growth of melanoma cells and its molecular mechanisms of action. Our present results have shown that LDE significantly suppressed the in vitro melanoma cell growth in dose- and time-dependent manners. LDE also displayed the synergistic effect with γ-radiation on the reduction of the cell viability in melanoma cells. The animal experimental results further confirmed that compared with the control group without drug treatment, the tumor volume in mice was significantly and time-dependently less in LDE group. The absolute weight of solid tumor in the LDE group was 7-fold lower than that in the control group. Western blot analysis indicated that LDE markedly down-regulated the expression of anti-apoptotic protein Bcl-2 and up-regulated the level of pro-apoptotic protein Bax, eventually leading the reduction of Bcl-2/Bax protein ratios both in the cultured melanoma cells and in the tumors from melanoma-bearing mice. In addition, LDE significantly reduced the tumor progression-associated protein levels of vascular endothelial growth factor (VEGF), hepatocyte growth factor/scatter factor (HGF/SF), and osteopontin (OPN) in tumors from the LDE-treated mice. Our findings suggest that LDE may have a wide therapeutic and/or adjuvant therapeutic application in the treatment of melanoma and other cancer.

Sailing injury and illness: results of an online survey

OBJECTIVE

The purpose of this study was to describe the relative frequency, patterns, and mechanisms of sailing-related injuries in dinghies and keelboats. Data were also collected on risky and risk-averse behaviors of sailors, as well as on sailing-related illnesses.

METHODS

A web-based, logic-driven, multiple-choice survey was developed and links were posted on sailing-related websites. Data were collected from March through November 2006 on any injuries or illnesses sailors sustained over the prior 12 months.

RESULTS

From 1188 respondents, a total of 1715 injuries and 559 illnesses was reported. The top 3 injuries for keel boats were leg contusions (11%), hand lacerations (8%), and arm contusions (6%), and in dinghies they were leg contusions (13%), knee contusions (6%), and leg lacerations (6%). The most common mechanisms of injury were "trip/fall," "hit by object," and "caught in lines." Tacking, heavy weather, and jibing were the most common factors contributing to injury. The rates of injury and severe injury in this internet-based survey were 4.6 and 0.57 per 1000 days of sailing, respectively. Of the 70 severe injuries, 25% were fractures, 16% were torn tendons or cartilage, 14% were concussions, and 8% were dislocations. The median rate of lifejacket use was 30%, and median rate of sunscreen use was 80%. Sixteen percent of sailors reported sunburn over the prior 12 months. Seven percent of sailors reported use of alcohol within the 2 hours preceding injury.

CONCLUSIONS

The most common injuries in both keel boats and dinghies are soft-tissue injuries to the extremities. Severe injuries and illnesses in sailing are uncommon in this study population.

Genetics of uveal melanoma and cutaneous melanoma: two of a kind?

Cutaneous melanoma and uveal melanoma both derive from melanocytes but show remarkable differences in tumorigenesis, mode of metastatic spread, genetic alterations, and therapeutic response. In this review we discuss the differences and similarities along with the genetic research techniques available and the contribution to our current understanding of melanoma. The several chromosomal aberrations already identified prove to be very strong predictors of decreased survival in CM and UM patients. Especially in UM, where the overall risk of metastasis is high (45%), genetic research might aid clinicians in selecting high-risk patients for future systemic adjuvant therapies.

The Role of B-RAF Mutations in Melanoma and the Induction of EMT via Dysregulation of the NF-κB/Snail/RKIP/PTEN Circuit

Melanoma is a highly metastatic cancer, and there are no current therapeutic modalities to treat this deadly malignant disease once it has metastasized. Melanoma cancers exhibit B-RAF mutations in up to 70% of cases. B-RAF mutations are responsible, in large part, for the constitutive hyperactivation of survival/antiapoptotic pathways such as the MAPK, NF-κB, and PI3K/AKT. These hyperactivated pathways regulate the expression of genes targeting the initiation of the metastatic cascade, namely, the epithelial to mesenchymal transition (EMT). EMT is the result of the expression of mesenchymal gene products such as fibronectin, vimentin, and metalloproteinases and the invasion and inhibition of E-cadherin. The above pathways cross-talk and regulate each other's activities and functions. For instance, the NF-κB pathway directly regulates EMT through the transcription of gene products involved in EMT and indirectly through the transcriptional up-regulation of the metastasis inducer Snail. Snail, in turn, suppresses the expression of the metastasis suppressor gene product Raf kinase inhibitor protein RKIP (inhibits the MAPK and the NF-κB pathways) as well as PTEN (inhibits the PI3K/AKT pathway). The role of B-RAF mutations in melanoma and their direct role in the induction of EMT are not clear. This review discusses the hypothesis that B-RAF mutations are involved in the dysregulation of the NF-κB/Snail/RKIP/PTEN circuit and in both the induction of EMT and metastasis. The therapeutic implications of the dysregulation of the above circuit by B-RAF mutations are such that they offer novel targets for therapeutic interventions in the treatment of EMT and metastasis.

Functional characterization of the progestagen-associated endometrial protein gene in human melanoma

Utilizing gene microarray profiling of melanoma samples, we have recently identified a novel gene overexpressed in both thick primary and metastatic melanomas. This gene, progestagen-associated endometrial protein (PAEP), has never before been implicated in the oncogenic processes of melanoma, with its true function in oncogenesis and tumour progression relatively unknown. Overexpression of the PAEP gene in freshly procured thick primary and metastatic melanoma samples (58%) and daughter cell lines (77%) is confirmed by quantitative RT-PCR, immunohistochemistry, Western blotting and mass spectrometric analysis. We suggest that PAEP gene overexpression is involved with melanoma tumour progression as well as an aggressive phenotype. Transfection of melanoma cells with PAEP small interfering RNA (siRNA) reveals a significant decrease in soft agar colony formation and a marked inhibition of both cell migration and cell invasion. Furthermore, we establish stable melanoma transfectants via PAEP lentiviral small hairpin RNA (shRNA), examine their growth characteristics in a murine xenograft model and reveal that tumour growth is significantly inhibited in two separate melanoma cell lines. Our data strongly implicate the PAEP gene as a tumour growth promoter with oncogenic properties and a potential therapeutic target for patients with advanced melanoma.